Heads up! This PR modifies the following files:

• @KiChjang: components/script/dom/htmlmetaelement.rs, components/script/dom/document.rs, components/net/http_loader.rs, components/script/dom/xmlhttprequest.rs, components/net_traits/lib.rs, components/net_traits/lib.rs, components/script/dom/htmliframeelement.rs, components/script/dom/webidls/Document.webidl

@nox - new (old) issue!

Please squash the two commits together.

-S-awaiting-review +S-needs-code-changes +S-needs-squash

Reviewed 8 of 8 files at r1, 48 of 48 files at r2.
Review status: all files reviewed at latest revision, 4 unresolved discussions, some commit checks failed.

components/msg/constellation_msg.rs, line 355 [r1] (raw file):

/// [Policies](https://w3c.github.io/webappsec-referrer-policy/#referrer-policy-states)
/// for providing a referrer header for a request
#[derive(HeapSizeOf, Clone, Deserialize, Serialize, Debug, Copy)]

Nit: alphanumeric order.

components/script/dom/document.rs, line 2804 [r1] (raw file):

    fn Referrer(&self) -> DOMString {
        //TODO - unimplemented, for ref pol tests
        DOMString::new()

Why don't we implement that? Should we remove it altogether for now if we can't? Or does that mean new test hacks?

components/script/dom/htmlmetaelement.rs, line 100 [r1] (raw file):

        https://html.spec.whatwg.org/multipage/#meta-referrer
        https://w3c.github.io/webappsec-referrer-policy/#set-referrer-policy
        */

So the spec is pretty clear, conceptually, the meta referrer policy is the referrer policy of the first meta name="referrer" element which satisfies all the conditions.

You should write a method on HTMLHeadElement that returns the first referrer policy it finds among the element children, and call this whenever there is a mutation somewhere that could change the referrer policy.

To do the second part, you will need to patch attribute_mutated, bind_from_tree and unbind_from_tree in the implementation of VirtualMethods for HTMLMetaElement.

components/script/dom/xmlhttprequest.rs, line 158 [r1] (raw file):

    fn new_inherited(global: GlobalRef) -> XMLHttpRequest {
        //TODO - will this panic (outside of the scope of the ref policy tests)?
        let current_doc = global.as_window().Document();

let (referrer_policy, referrer_url) = if let GlobalRef::Window(window) = global {
    let document = window.Document();
    (document.url().clone(), document.get_referrer_policy())
} else {
    (None, None)
};

And please put a todo about doing this correctly for workers.

Comments from Reviewable

☔ The latest upstream changes (presumably #11413) made this pull request unmergeable. Please resolve the merge conflicts.

Review status: all files reviewed at latest revision, 4 unresolved discussions, some commit checks failed.

components/msg/constellation_msg.rs, line 355 [r1] (raw file):

components/script/dom/document.rs, line 2804 [r1] (raw file):

components/script/dom/htmlmetaelement.rs, line 100 [r1] (raw file):

components/script/dom/xmlhttprequest.rs, line 158 [r1] (raw file):

Comments from Reviewable

The mozilla-specific tests were modified to not require document.referrer any more, so I think it would make sense to remove the stub implementation.

Reviewed 6 of 6 files at r3.
Review status: all files reviewed at latest revision, 2 unresolved discussions, some commit checks failed.

components/script/dom/document.rs, line 2804 [r1] (raw file):

Comments from Reviewable

New code was committed to pull request.

Review status: 53 of 56 files reviewed at latest revision, 1 unresolved discussion.

components/script/dom/htmlmetaelement.rs, line 100 [r1] (raw file):

Comments from Reviewable

-S-awaiting-review +S-needs-code-changes

Ssssssh... Do you hear it? Do you hear the merge coming to us, slowly but surely? :)

Reviewed 2 of 2 files at r4, 2 of 2 files at r5.
Review status: all files reviewed at latest revision, 3 unresolved discussions.

components/script/dom/htmlheadelement.rs, line 43 [r5] (raw file):

    pub fn set_document_referrer(&self) {
        //TODO is this THE head element, or any? If any, should confirm it's the one
        //on second thought, may not matter if this is only called from the metaelements

I think you can instead call this from HTMLMetaElement if the parent of the meta element is a head, and check here whether that head is the head element.

components/script/dom/htmlheadelement.rs, line 50 [r5] (raw file):

                           .filter(|elem| elem.get_string_attribute(&atom!("name")) == "referrer")
                           .filter(|elem| elem.get_attribute(&ns!(), &atom!("content")).is_some());

Nit: unneeded blanks.

components/script/dom/htmlmetaelement.rs, line 100 [r1] (raw file):

Comments from Reviewable

💔 Test failed - linux-rel

I'm pretty sure this is intermittent.

Filed #11561.

Review status: all files reviewed at latest revision, 3 unresolved discussions, some commit checks failed.

components/script/dom/htmlheadelement.rs, line 48 [r6] (raw file):

components/script/dom/htmlmetaelement.rs, line 108 [r6] (raw file):

Comments from Reviewable

New code was committed to pull request.

Remove the TODO comment that you forgot and r=me. Great work!

-S-awaiting-review +S-needs-code-changes

Reviewed 2 of 2 files at r8.
Review status: all files reviewed at latest revision, 3 unresolved discussions.

components/script/dom/htmlheadelement.rs, line 48 [r6] (raw file):

components/script/dom/htmlmetaelement.rs, line 108 [r6] (raw file):

Comments from Reviewable

New code was committed to pull request.

Should be set. I believe my 'todos' are in order as well. Woot woot!

@bors-servo r=nox

📌 Commit 687d0cd has been approved by nox

⌛ Testing commit 687d0cd with merge 530b5a6...

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel, mac-dev-unit, mac-rel-css, mac-rel-wpt, windows